Verifi reports indicate the initial slump and leave plant slump. Initial slump is the first valid slump determined by Verifi after post-batch mixing is complete. Leave plant slump is determined when Verifi GPS shows the truck has left the boundary of the plant.
Here’s how both can be used.
How Verifi Changes Things
Without Verifi, drivers typically adjust the slump in the plant to slightly above target. The hope is for the slump to be relatively close to target upon reaching the jobsite.
Verifi adjusts slump in transit; therefore, it is no longer necessary to batch above the target slump. Verifi recommends batching at or slightly below the target slump. Drivers can load, mix, and go, then let Verifi adjust slump in transit up to the target slump. This can save significant time in the plant.
Leave Plant Slump
The reason to check the leave plant slump with Verifi is to ensure drivers do not leave with a load batched significantly above target and likely to be rejected at the jobsite.
Otherwise, the concrete does not care where it is, so the slump at leave plant is not relevant to concrete quality.
The initial slump can be used to assess how closely slump is batched to target. Variations in initial slump can suggest poor batching, a change in aggregate moisture, or a change in materials. This feedback can be highly useful for batching subsequent loads closer to target and identifying needed mix design changes.
Without Verifi, both initial and leave plant slump are important. With Verifi, initial slump is much more useful that leave plant slump.